基于表面等离子波耦合的流体波导光栅耦合器

提出了一种由金属光栅和流体光波导结构组成的,基于表面等离子波耦合的光栅耦合器。利用光栅的衍射效应,将金属光栅与介质分界面之间产生的表面等离子波耦合到流体光波导中,并且能够沿着流体光波导稳定地向前传播。通过采用基于有限时域差分算法的FDTD Solutions软件对光栅耦合器进行了参数优化及特性分析,通过优化使该结构在650 nm波长下的耦合效率达到56%。此外,由于该结构对TE偏振光和TM偏振光的选择比达到70∶1,因此具有偏振器的功能。同时由于TE偏振光耦合频谱的频带宽度仅为20 nm,该结构还具有窄带滤波的作用。此外,还研究了光栅结构参数、入射角以及流体折射率对耦合频谱的影响。

Liquid Waveguide Grating Couplers Based on the Surface Plasmon Wave Coupling

A grating coupler coupled based on the surface plasma wave was proposed,consisting of metal gratings and the liquid optical waveguide.The surface plasma wave produced on the interface between the metal gratings and dielectric interface was coupled into the liquid optical waveguide by the diffraction effect of the gratings,and could be able to propagate steadily along the liquid optical waveguide.Finite difference time domain(FDTD) solutions software based on the FDTD method was employed to optimize the parameters and analyze the characteristic for the grating coupler.As a result,the coupling efficiency is up to 56% at the wavelength of 650 nm through the optimization.Besides that,the selection ratio of the structure between the TE and TM polarized light is up to 70∶1,therefore the coupler can also be as a polarizer.What's more,the structure had a function of a filter due to the frequency bandwidth of the TM polarized light coupling spectrum of 20 nm,and the structure also has narrow-band filter characteristics.Finally,the effect of the grating structure parameters,incident angle and liquid index on the coupling spectrum was studied.